1. Field of the Invention:
This invention relates to distance measuring devices and more particularly to distance measuring devices capable of measuring a plurality of objects distances at the same time.
2. Description of the Prior Art:
In the art of distance measuring devices of this type, it has been proposed to employ a plurality of light emitting elements along with the corresponding number of light receiving elements as, for example, disclosed in U.S. patent application Ser. No. 577,089 filed Feb. 6, 1984, or to construct the projection lens in a form having a plurality of optical axes, or of a so-called ommateal lens as disclosed in U.S. Pat. No. 4,371,261. However, the former, because of its having a plurality of elements, calls for a large increase in the bulk and size of the device, and, therefore, is very disadvantageous from the standpoint of space and cost, making it difficult to be put into practice. The latter, because of its use of the lens in divided areas, requires either that the lens be increased in size or that if the lens is greatly small, the output of the light emitting element is increased to a large extent to compensate for the reduction of the amount of light transmitted through the lens. This also was very difficult to put into practical use.
A first object of the present invention is to eliminate the above-described drawbacks of the conventional device and to provide a distance measuring device in which a light beam is projected onto an object, and its reflection is received to measure the distance to the object, whereby the light beam to be projected onto the object is divided into a plurality of directions by a reflecting system, so that with a very simple and compact structure a plurality of object distances can feasibly be measured at one time.
Other objects of the invention will become apparent from the following detailed description of embodiments thereof.